use std::error::Error;
use std::{env, fs};

pub fn run(config: Config) ->Result<(), Box<dyn Error>> {
    let prt_path=config.file_path.clone();
    let contents = fs::read_to_string(config.file_path)?;

    let results:Vec<&str>= if !config.ignore_case {
        search_case_sensitive(&config.query, &contents)
    } else {
        search_case_insensitive(&config.query, &contents)
    };

    println!("搜索对应文件包含对应字符串的所在行");
    println!("搜索的文件：{}",prt_path);
    println!("搜索的字符串：{}",config.query);
    println!("设置的环境变量-忽略大小写(IGNORE_CASE)：{}",config.ignore_case);
    println!("搜索到的行结果：");
    for line in results{
        println!("{}", line);
    }

    Ok(())
}

pub struct Config {
    pub query: String,
    pub file_path: String,
    pub ignore_case: bool,
}

impl Config {
    pub fn build(mut args: impl Iterator<Item=String>) -> Result<Config, &'static str> {
        args.next();
        let query=match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a query string"),
        };
        let file_path= match args.next() {
            Some(arg) => arg,
            None => return Err("Didn't get a file name"),
        };

        let result_var= env::var("IGNORE_CASE");
        let has_var=result_var.is_ok();
        let mut ignore_case = false;
        if has_var {
            if result_var.unwrap().as_str()=="true"{
                ignore_case = true;
            }
        }
		
        Ok(Config{query, file_path, ignore_case})
    }
}

pub fn search_case_sensitive<'a>(query:&str,contents:&'a str)->Vec<&'a str> {
    contents
        .lines()
        .filter(|line| {line.contains(query)})
        .collect()
}

pub fn search_case_insensitive<'a>(
    query: &str,
    contents: &'a str
) -> Vec<&'a str> {
    let query = query.to_lowercase();
    contents
        .lines()
        .filter(|line| {line.to_lowercase().contains(&query)})
        .collect()
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn case_sensitive() {
        let query="duct";
        let contents = "\
Rust:
safe,fast,productive.
Pick three.
Duct tape.";
        assert_eq!(vec!["safe,fast,productive."],search_case_sensitive(query, contents));
    }

    #[test]
    fn case_insensitive() {
        let query="rUst";
        let contents = "\
Rust:
safe,fast,productive.
Pick three.
Trust me.";
        assert_eq!(vec!["Rust:", "Trust me."],search_case_insensitive(query, contents));
    }

}
